The present invention relates to a semiconductor device and a method for manufacturing the same.
The resistance of a resistive element is preferably stable with respect to variations in the temperature of the environment. For this reason, resistive elements are required to have a smaller temperature coefficient of resistance. Various resistive elements, resistors, or the like, including those described below, have been proposed.
Japanese Unexamined Patent Publication No. 2001-332402 discloses a resistive material. The resistive material essentially consists of four elements-Al, B, Cr, and Si. The resistive element has a resistivity of 4 mΩ·cm or more and an absolute temperature coefficient of resistance of 300 ppm/° C. or less. Thus, the Publication states that it is possible to provide a resistive element having a small absolute temperature coefficient of resistance and a large resistivity.
Japanese Unexamined Patent Publication No. 2007-073651 discloses a thin-film resistor which is formed over a substrate having electrical insulation properties and which contains a Cr—Al—Si ternary alloy. By adjusting the composition ratio of the elements, the resistivity of the thin-film resistor becomes 500 μΩ·cm or more; the absolute temperature coefficient of resistance becomes 50 ppm/° C. or less; and the rate of change of the resistance after maintained at 155° C. for 1000 hours becomes 0.05% or less. Thus, the Publication states that it is possible to provide a highly heat-resistant thin-film resistor which has a high resistivity and a low temperature coefficient of resistance and which exhibits a low resistance change rate when heated during operation.
Japanese Unexamined Patent Publication No. 2008-010604 discloses a thin-film resistive material that contains 20 to 60 mass % of Ta, 2 to 10 mass % of Al, 0.5 to 15 mass % of Mo, and the balance containing Cr and Ni where a mass ratio Cr/Ni is 0.75 to 1.1. Thus, the Publication states that a thin-film resistor using this thin-film resistive material has a significantly improved volume resistance and salt water resistance, compared to a conventional thin-film resistor using a resistive thin film containing a Ni—Cr—Al—Si alloy.
Japanese Unexamined Patent Publication No. Hei6-275409 discloses the following method for manufacturing a thin-film resistive element. A TaN layer is formed by sputtering Ta in an atmosphere of a mixed gas of a noble gas element selected from the group consisting of Ne, Ar, Kr, and Xe, and nitrogen. A noble gas element is sputtered onto the TaN layer using a RF electrode apparatus. Thus, the Publication states that a temperature coefficient of resistance close to 0 ppm/° C. can be obtained stably without requiring vacuum annealing.
Japanese Unexamined Patent Publication No. 2004-342705 discloses the following TaN thin-film resistor. An electrode film is formed over the top surface of a TaN thin film formed over an insulating substrate with an intermediate film therebetween. Referring to the combined temperature coefficient of resistance of the intermediate film and the electrode film as a first temperature coefficient of resistance and to the temperature coefficient of resistance of the thin-film resistor as a second temperature coefficient of resistance, the sum of the first and second temperature coefficients of resistance is set to −10 ppm/° C. to 0 ppm/° C. Thus, the Publication states that the temperature coefficient of resistance can be kept small across the entire operating temperature region in consideration of the contact resistance of the electrode film.
Japanese Unexamined Patent Publication No. 2009-021509 discloses a semiconductor device. The semiconductor device includes a resistive element containing nitrogen and tantalum as main constituent elements disposed over the main surface of a substrate. The top region of the resistive element, which is located opposite to the substrate, has a nitrogen concentration of 30 at % or more. Thus, the Publication states that it is possible to provide a semiconductor device including a resistive element having a low parasitic capacitance and a resistance which varies to a lesser extent when subjected to heat treatment.
Japanese Unexamined Patent Publication No. 2002-043102 discloses a thin-film resistor for inkjet printer. This thin-film resistor contains TaSiN having a high Si concentration. The TaSiN thin film has a Si concentration (Si/(Si+Ta)) between 40% and 80% and a N concentration between 2.5% and 50%. Thus, the Publication states that it is possible to provide a thin-film resistor which has a high resistivity and a small temperature coefficient of resistance and which can be uniformly heated as a heater material.
Japanese Unexamined Patent Publication No. Sho62-224002 discloses the following method for manufacturing a thin-film chip resistor. First, a resistive film containing NiCr, TaN, or the like is deposited over an entire surface of a substrate by vapor deposition, sputtering, or the like. Subsequently, a metal film to serve as an electrode is deposited. Subsequently, the resistive film is patterned. Further, a SiN film to serve as a protective film is formed over the resistive film by chemical vapor deposition (CVD). Thus, the Publication states that it is possible to provide a thin-film chip resistor which is significantly stable with respect to the resistance and the rate of change thereof.